PubMed · 7899490
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J E Upledger. 1995. Craniosacral therapy.. https://doi.org/10.1093/ptj%2F75.4.328
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In rhythmic movements, humans activate their muscles in a robust and energy efficient way. These activation patterns are oscillatory and seem to originate from neural networks in the spinal cord, called central pattern generators (CPGs). Evidence for the existence of CPGs was found for instance in lampreys, cats and rats. There are indications that CPGs exist in humans as well, but this is not proven yet. Energy efficiency is achieved by resonance tuning: the central nervous system is able to tune into the resonance frequency of the limb, which is determined by the local reflex gains. The goal of this study is to investigate if the existence of a CPG in the human spine can explain the resonance tuning behavior, observed in human rhythmic limb movement. A neuro-musculo-skeletal model of the forearm is proposed, in which a CPG is organized in parallel to the local reflexloop. The afferent and efferent connections to the CPG are based on clues about the organization of the CPG, found in literature. The model is kept as simple as possible (i.e., lumped muscle models, groups of neurons are lumped into half-centers, simple reflex model), but incorporates enough of the essential dynamics to explain behavior-such as resonance tuning-in a qualitative way. Resonance tuning is achieved above, at and below the endogenous frequency of the CPG in a highly non-linear neuro- musculo-skeletal model. Afferent feedback of muscle lengthening to the CPG is necessary to accomplish resonance tuning above the endogenous frequency of the CPG, while feedback of muscle velocity is necessary to compensate for the phase lag, caused by the time delay in the loop coupling the limb to the CPG. This afferent feedback of muscle lengthening and velocity represents the Ia and II fibers, which-according to literature-is the input to the CPG. An internal process of the CPG, which integrates the delayed muscle lengthening and feeds it to the half-center model, provides resonance tuning below the endogenous frequency. Increased co-contraction makes higher movement frequencies possible. This agrees with studies of rhythmic forearm movements, which have shown that co-contraction increases with movement frequency. Robustness against force perturbations originates mainly from the CPG and the local reflex loop. The CPG delivers an increasing part of the necessary muscle activation for increasing perturbation size. As far as we know, the proposed neuro-musculo-skeletal model is the first that explains the observed resonance tuning in human rhythmic limb movement.
We assessed the safety and efficacy of orally administered CC chemokine receptor 1 (CCR1) antagonist in 105 patients with relapsing/remitting MS (RRMS) in a 16-week, randomized, double-blind, placebo-controlled trial. The primary endpoint was the cumulative number of newly active lesions on serial MRI scans. Other MRI, immunologic, and clinical outcomes were also explored. No significant treatment difference was observed for any tested MRI variable. CCR1 does not contribute to initial leukocyte infiltration in RRMS.
INTRODUCTION AND DEVELOPMENT: Ultrasonography is the preferred diagnostic imaging technique for studying the intrauterine foetus. Yet, occasionally certain circumstances arise where it is necessary to use other techniques in order to achieve a better analysis of the foetal structures. The development of ultra-high speed magnetic resonance imaging (MRI) has now been applied to the study of the foetus, since it allows images to be obtained in extremely short times and the effects of movements by the mother or the foetus have little influence on the results. It is a type of imaging that does not use ionising radiations and offers high contrast images in any plane without being influenced by the physical characteristics of the expectant mother or the position of the foetus. AIMS: To make the technique and the use of MRI in foetal studies more widely known, as well as to review the role played by MRI in the study and treatment of foetal deformations of the central nervous system detected within the uterus. CONCLUSIONS: Anomalies of the central nervous system constitute the most frequent cause of visits for prenatal diagnosis. They usually have a poor prognosis due to the likelihood of important sequelae and are a cause of great concern to the parents. They are often associated with genetic and chromosomal disorders.